Disposable diaper

Abstract

To provide a disposable diaper which is comfortable to wear. [Solution] This disposable diaper comprises a top sheet (1), a back sheet (2), an absorber (3) and a stretchable sheet (4). The stretchable sheet (4) is composed by having a base material sheet (41) sandwich multiple elastic stretchable members (42) disposed therein in an extended state, said multiple elastic stretchable members (42) being disposed along the width direction of the disposable diaper and spaced apart at intervals in the longitudinal direction. When viewed in the width direction, the stretchable sheet (4) has an overlapping portion (43) which includes a region that overlaps with a part of the absorber (3). In the overlapping portion (43), the multiple elastic stretchable members (42) are disposed continuously along the width direction. The multiple elastic stretchable members (42) are not joined to the sides of the base material sheet (41) at the central region (43a) of the overlapping portion (43), said central region (43) being where part of the absorber (3) is overlapped, and are joined to the sides of the base material sheet (41) at the side regions (43b) of the overlapping portion (43) which are positioned to the outside of the central region (43a) in the width direction.

Description

[0001] The present invention relates to a disposable diaper worn between the legs of a wearer to absorb and retain liquids such as urine. More specifically, the present invention relates to a disposable diaper in which an expandable sheet, constructed by sandwiching an elastic expandable member between base sheets, is placed in the abdominal area on the front or back of the diaper, making the waist area expandable.

[0002] Conventionally, disposable diapers of the pant type or tape type have been known in which the abdominal area of ​​the front and back panels is made stretchable in order to improve the closeness with the wearer's body. In order to make the waist area of ​​a disposable diaper stretchable, it is conceivable to use a woven fabric (stretch fabric) that has elasticity in itself, but this is too costly to use in disposable diapers. For this reason, a technique is known in which a stretchable sheet is formed by bonding a thread-like or strip-like elastic stretchable member to a non-stretchable sheet such as a nonwoven fabric or plastic film in an extended state, and this stretchable sheet is placed around the waist of a disposable diaper.

[0003] As disposable diapers having the stretchable sheet described above, for example, the inventions disclosed in Patent Document 1 and Patent Document 2 are known. In the disposable diaper disclosed in Patent Document 1, an absorbent material is interposed between the top sheet and the back sheet, and an elastic sheet is provided in the abdominal area on the back or front side. This elastic sheet is formed by bonding multiple elastic stretch members in an extended state between base sheets. In the disposable diaper of Patent Document 1, the elastic stretch members included in the elastic sheet are finely cut in the area overlapping with the absorbent material, making them non-stretchable. Furthermore, the disposable diaper disclosed in Patent Document 2, like the disposable diaper in Patent Document 1, forms an expandable sheet by joining elastic strands to a base sheet in an extended state, and places this expandable sheet in the abdominal area of ​​the disposable diaper. In the disposable diaper disclosed in Patent Document 2, the elastic expandable member included in the expandable sheet is pressed by embossing in the area that overlaps with the absorbent material, and in this pressed area, there are no elastic strands, or if there are, they are in a non-stretchable state.

[0004] In the disposable diaper described in Patent Document 1 and Patent Document 2, in the region where the absorber and the stretch sheet overlap, the elastic stretch member (elastic strand) is in a non-stretched state. By adopting such a configuration, it is said that when the stretch sheet shrinks, it is possible to prevent the absorber from being distorted or wrinkled, and the wearing feeling of the diaper from deteriorating.

[0005] Japanese Patent Application Laid-Open No. 2008-29749, Japanese Patent Application Laid-Open No. 2006-198207

[0006] However, when the elastic stretch member disposed in the abdominal circumference portion is in a non-stretched state in the region overlapping the absorber as in the technology disclosed in the above patent documents, a gap is formed between the absorber and the abdominal circumference of the wearer when wearing the disposable diaper, and there is a problem that the adhesion of the diaper decreases. When the adhesion between the diaper and the wearer decreases, there are problems that the sheet member constituting the diaper rubs against the skin of the wearer and causes injury, or that urine leakage cannot be surely prevented.

[0007] Here, in order to solve the above problem, it is conceivable to exhibit the elasticity of the stretch sheet disposed in the abdominal circumference portion even in the region overlapping the absorber. However, when the elasticity of the stretch sheet is exhibited in the region overlapping the absorber, the elastic force of the elastic stretch member is directly transmitted to the absorber, and still, the absorber is distorted or wrinkled, leading to a situation where the wearing feeling of the diaper deteriorates. ​

[0009] The inventors of the present invention diligently considered means to solve the problems of the prior art described above, and as a result, they decided to place a stretchable sheet, formed by sandwiching a plurality of elastic stretchable members between base sheets, in the abdominal area of ​​the diaper, and to include the elastic stretchable members contained in the stretchable sheet in the area that overlaps with the absorbent, while not joining the elastic stretchable members in this overlapping area to the base sheet. As a result, since elastic stretchable members are also present in the area where the stretchable sheet and the absorbent overlap, the close contact between the absorbent and the wearer's abdominal area can be maintained. Furthermore, since the elastic stretchable members located in the area where the stretchable sheet and the absorbent overlap are not joined to the base sheet, their elasticity is not directly transmitted to the absorbent, thus preventing wrinkles and creases from forming in the absorbent. The inventors of the present invention then realized that the problems of the prior art could be solved based on the above findings, and completed the present invention. To explain in more detail, the present invention has the following configuration.

[0010] The present invention relates to disposable diapers. The disposable diaper of the present invention comprises a liquid-permeable top sheet 1, a liquid-impermeable back sheet 2, an absorbent material 3 interposed between the top sheet 1 and the back sheet 2 in a portion including the crotch area, and a stretchable sheet 4 interposed between the top sheet 1 and the back sheet 2 in a portion of both or either the front and back of the garment. Here, the expandable sheet 4 comprises a base sheet 41 and a plurality of elastic expandable members 42 that are arranged between the base sheet 41 in an expanded state, extending along the width direction of the disposable diaper and spaced apart in the length direction. Furthermore, the stretchable sheet 4 has an overlapping portion 43 that, when viewed in the width direction, includes an area that overlaps with a part of the absorbent 3. Furthermore, the multiple elastic stretch members 42 are arranged continuously along the width direction in the overlapping portion 43. Furthermore, in the central region 43a of the overlapping portion 43 that overlaps with a part of the absorber 3, the multiple elastic stretch members 42 are not joined between the base sheets 41, but in the lateral region 43b of the overlapping portion 43 that is located outside the width direction of the central region 43a, they are joined between the base sheets 41.

[0011] As described above, the multiple elastic stretch members 42 included in the stretchable sheet 4 are located in the central region 43a that overlaps with the absorbent 3, but are not joined between the base sheets 41. By having elastic stretch members 42 in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap, when the elastic stretch members 42 contract, the absorbent 3 adheres closely to the wearer's skin. Furthermore, the presence of elastic stretch members 42 in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap maintains the elasticity of the stretchable sheet 4, allowing the waist area of ​​the diaper to stretch very well and improving the wearing comfort. On the other hand, in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap, the elastic stretch members 42 are not joined between the base sheets 41, so even when the elastic stretch members 42 contract, the absorbent 3 is not pushed inward in the width direction, preventing wrinkles and creases from forming in the absorbent. In this way, the present invention simultaneously achieves maintaining the adhesion of the absorbent and preserving the shape of the absorbent.

[0012] In the present invention, it is preferable that the stretchable sheet 4 further includes a non-overlapping portion 44 that does not overlap with the absorber 3 when viewed in the width direction. Furthermore, it is preferable that the plurality of elastic stretchable members 42 are arranged continuously along the width direction in the non-overlapping portion 44 and joined between the base sheet 41.

[0013] As described above, the stretchable sheet 4 includes a non-overlapping portion 44 which is a region that extends in the width direction without overlapping with the absorbent body 3. In this non-overlapping portion 44, a plurality of elastic stretchable members 42 are continuously arranged and joined between the base sheet 41, thereby improving the adhesion not only to the edges of the absorbent body 3 but also to the surrounding areas. This further improves the comfort of wearing the diaper.

[0014] Preferably, the disposable diaper of the present invention further comprises at least one pair of fastening portions 5 attached to the left and right sides of the front or back of the diaper, so as to protrude outward in the width direction from the left and right side edges. These fastening portions 5 can be fastened to the outer surface of the front or back of the diaper, and by fastening the fastening portions 5 to the outer surface of the diaper, the disposable diaper can be attached around the wearer's waist. In this case, the stretchable sheet 4 is positioned on the front or back of the garment where the fastening portion 5 is provided. Preferably, the multiple elastic stretchable members 42 included in the stretchable sheet 4 are located inward in the width direction from the fixed ends to which the fastening portions 5 are fixed on both the left and right sides.

[0015] As described above, it is preferable that the elastic stretch members 42 included in the stretchable sheet 4 be located on the inside in the width direction of the fixed ends of the pair of fastening parts 5. The space between the pair of fastening parts 5 corresponds to the waist area of ​​the diaper. Therefore, by providing elasticity between the pair of fastening parts 5, the wearer can pull on the fastening parts 5 when putting on the diaper. In addition, by providing elasticity between the pair of fastening parts 5, the waist area of ​​the diaper becomes more comfortable. Furthermore, it is preferable that the width direction ends of the multiple elastic stretch members 42 included in the stretchable sheet 4 do not overlap with the fixed ends of the fastening parts 5. If the width direction ends of the elastic stretch members 42 overlap with the fastening parts 5, the fastening parts 5 will deform when the elastic stretch members 42 contract, reducing the operability of the fastening parts 5 and making it difficult to put on the disposable diaper. In this regard, such problems can be avoided by ensuring that the width direction ends of the elastic stretch members 42 do not overlap with the fixed ends of the fastening parts 5.

[0016] In the present invention, it is preferable that the plurality of elastic stretch members 42 included in the stretchable sheet 4 are arranged at substantially constant intervals in the longitudinal direction. Here, "substantially constant" includes not only cases where the intervals of the plurality of elastic stretch members 42 are perfectly the same, but also cases where the plurality of elastic stretch members 42 are arranged at intervals within an error range of ±5% or less when the average value of the intervals of the plurality of elastic stretch members 42 is taken as 100%.

[0017] As described above, by arranging the multiple elastic stretch members 42 at approximately constant intervals, gathers (folds) are uniformly formed around the waist of the diaper, improving the appearance of the diaper.

[0018] In the present invention, it is preferable that the stretchable sheet 4 is positioned at a distance from the edge in the longitudinal direction of the front or back body piece on which the stretchable sheet 4 is placed.

[0019] As described above, by arranging the stretchable sheet 4 at a distance from the longitudinal edge of the diaper, the hardness of the stretchable sheet 4 itself is less likely to be transmitted to the wearer, improving the comfort of wearing the diaper.

[0020] In the present invention, it is preferable that the base sheet 41 included in the stretchable sheet 4 overlaps in two or more layers between the elastic stretchable member 42 and the absorber 3 in the overlapping portion 43.

[0021] As described above, in the present invention, the elastic stretch member 42 is not joined between the base sheet 41 in the central region 43a where the stretch sheet 4 and the absorbent 3 overlap, so that the absorbent 3 does not deform even when the stretch sheet 41 contracts. In a preferred embodiment of the present invention, in order to further improve the above effect, the base sheet 41 is layered two or more times between the elastic stretch member 42 and the absorbent 3 in the overlapping portion 43 which includes the region where the stretch sheet 4 overlaps with the absorbent 3. As a result, the base sheet 41 at the point of contact with the absorbent 3 is layered two or more times, so that the contracting force of the elastic stretch member 42 is further reduced to be transmitted to the absorbent 3, and the amount of deformation of the absorbent 3 can be suppressed.

[0022] In this invention, although the multiple elastic stretch members 42 included in the stretchable sheet 4 are located in the central region 43a that overlaps with the absorbent 3, they are not joined between the base sheet 41. By having the elastic stretch members 42 in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap in this way, when the elastic stretch members 42 contract, the absorbent 3 will adhere closely to the wearer's skin. Furthermore, because the elastic stretch members 42 are located in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap, the stretchability of the stretchable sheet 4 is maintained, allowing the waist area of ​​the diaper to stretch very well and improving the wearing comfort. On the other hand, in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap, the elastic stretch members 42 are not joined between the base sheet 41, so even when the elastic stretch members 42 contract, the absorbent 3 will not be pushed inward in the width direction, preventing wrinkles and creases from forming in the absorbent. In this way, the present invention simultaneously achieves maintaining the adhesion of the absorbent and preserving the shape of the absorbent.

[0023] Figure 1 shows an example of a disposable diaper according to an embodiment of the present invention.Figure 1(a) shows an unfolded view of the disposable diaper.Figure 1(b) shows an enlarged view of the stretchable sheet.Figure 2 shows an outline of the cross-section of the line Y1-Y1 shown in Figure 1.Figure 3 shows an outline of the cross-section of the line Y2-Y2 shown in Figure 1.Figure 4 shows an example of the structure of the stretchable sheet included in the disposable diaper of the present invention.Figure 4(a) shows an example in which the base sheet is formed by folding one sheet member in half.Figure 4(b) shows an example in which the base sheet is formed by two sheet members.Figure 4(c) shows an example in which the base sheet is made up of one sheet member and its cross-section is formed in the shape of an eight.Figure 5 shows an example of the structure of the stretchable sheet included in the disposable diaper of the present invention.Figure 5(a) shows an example in which the cross-section of one base sheet is in the shape of an eight, and the base sheet is doubled between the elastic stretchable member and the absorbent material. Figure 5(b) shows an example in which an elastic stretch member is enclosed by a single base sheet, with the base sheet overlapping twice between the elastic stretch member and the absorbent. Figure 6 shows an example of the structure of the stretch sheet included in the disposable diaper of the present invention. Figure 6(a) shows an example in which the inner and outer surfaces of a folded stretch sheet are joined to each other in the gap region of the elastic stretch member. Figure 6(b) shows an example in which the outer surface of a folded stretch sheet has a protrusion in the gap region of the elastic stretch member. Figure 6(c) shows an example in which the inner and outer surfaces of the base sheet are heat-sealed in the gap region of the elastic stretch member using a hot needle. Figure 6(d) shows an example in which the elastic stretch member is fixed with wrinkles formed on the inner and outer surfaces of the stretch sheet.

[0024] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, but also includes modifications made to the following embodiments to the extent that is obvious to those skilled in the art. In this specification, "A to B" means "A or greater and B or less". Furthermore, in this specification, "length direction" refers to the length direction of a vertically elongated disposable diaper, and means the direction connecting the front and back panels of the disposable diaper (up and down direction in Figure 1). Also, "width direction" refers to the width direction of a vertically elongated disposable diaper, and means the direction perpendicular to the length direction in a planar manner (left and right direction in Figure 1). Also, "thickness direction" refers to the direction in which the sheet members constituting the disposable diaper overlap, and means the direction perpendicular to the length direction and width direction in three dimensions (left and right direction in Figure 2). Furthermore, in each figure, orthogonal coordinates X, Y, and Z are shown to facilitate understanding of direction in three-dimensional space. In each figure, the X axis represents the width direction, the Y axis represents the length direction, and the Z axis represents the thickness direction.

[0025] Figure 1(a) is an unfolded view showing an example of a tape-type disposable diaper 100, and shows the disposable diaper as viewed from the side that comes into contact with the wearer's skin when worn (skin-contact side). Figure 1(b) is a conceptual diagram showing an enlarged and extracted view of the stretchable sheet 4 included in the disposable diaper. As shown in Figure 1(a), the tape-type disposable diaper 100 has a vertical shape and is divided along its length into a front section 101 that covers the wearer's abdomen when worn, a back section 102 that covers the wearer's back, and a crotch section 103 that is placed between the wearer's legs.

[0026] The crotch area 103 is the part located between the front panel 101 and the back panel 102. The disposable diaper 100 has an absorbent body 3 arranged around the crotch area 3, extending from the front panel 101 to the back panel 102. The absorbent body 3 has the function of absorbing and retaining liquids such as urine. For example, the absorbent body 3 is constructed by covering an absorbent material 31 for absorbing and retaining the wearer's urine and bodily fluids with a core wrap sheet 32 ​​from the skin-contacting side and the non-skin-contacting side. As the absorbent material 31, for example, a mat made by mixing fluff pulp and a super absorbent polymer (SAP) can be used. An example of fluff pulp is wood pulp or non-wood pulp that has been defibrated into a cotton-like form. An example of a super absorbent polymer is sodium polyacrylate. The core wrap sheet 32 ​​is made of a hydrophilic sheet. As the hydrophilic sheet, for example, tissue paper, absorbent paper, or a nonwoven fabric that has been treated to be hydrophilic can be used. The shape of the absorbent body 3 is preferably such that, when viewed from above as shown in Figure 1(a), an absorbent material 31 molded into, for example, an hourglass shape is enclosed between rectangular core wrap sheets 32. However, the shape of the absorbent material 31 can also be any known shape such as rectangular, gourd-shaped, or T-shaped.

[0027] The absorbent body 3 is covered from the side that comes into contact with the wearer's skin (skin-contact side) by a liquid-permeable top sheet 1, and from the opposite side that does not come into contact with the skin (non-skin-contact side) by a liquid-impermeable back sheet 2. Therefore, liquids such as urine permeate through the top sheet 1 and are absorbed and retained by the absorbent body 3, and leakage to the outside is prevented by the back sheet 2. As the liquid-permeable material constituting the top sheet 1, for example, woven fabric, nonwoven fabric, or porous film can be used. In particular, as the liquid-permeable material, it is preferable to use a nonwoven fabric made of a thermoplastic resin such as polypropylene, polyethylene, polyester, or nylon that has been treated to be hydrophilic. As the liquid-impermeable material constituting the back sheet 2, for example, a liquid-impermeable film made of a resin such as polyethylene can be used. In particular, it is preferable to use a microporous polyethylene film as the liquid-impermeable material. This microporous polyethylene film has numerous fine pores of about 0.1 μm in size, and although it is impermeable to liquids, it is permeable to moisture, thus preventing stuffiness inside the diaper.

[0028] In addition, a pair of left and right side sheets 6 may be provided on both sides in the width direction of the absorbent body 3. Preferably, the side sheets 6 are made of a material that is hydrophobic but also highly breathable. Alternatively, a three-dimensional gather may be formed by fixing one end of the side sheet 6 onto the surface of the top sheet 1 and fixing a three-dimensional gather stretchable member 61 to the other end in an extended state. When the three-dimensional gather stretchable member 61 contracts, the three-dimensional gather stands upright in the direction that it comes into contact with the wearer's skin, utilizing the contraction force. The upright three-dimensional gather functions as a leak-proof wall to prevent liquid from leaking from the left and right sides of the top sheet 1. Alternatively, a leg-around gather may be formed by fixing a leg-around gather stretchable member 62 in an extended state near the portion of the side sheet 6 that forms the opening around the legs. Forming a leg-around gather improves the fit around the wearer's legs when the diaper is put on.

[0029] In addition, a cover sheet 7 (see Figure 2) may be laminated to the side of the back sheet 2 that does not come into contact with the skin in order to reinforce the back sheet 2 and improve its feel. As the material for forming the cover sheet 7, for example, a nonwoven fabric made of a thermoplastic resin such as polyethylene, polypropylene, or polyester, or a wet-laid nonwoven fabric can be used.

[0030] As shown in Figure 1, the tape-type disposable diaper 100 has side flaps 101a and 102a extending to the left and right sides in the width direction on the front and back panels 101 and 102, respectively. A pair of fastening parts 5 are attached to the side flaps 102a formed on the back panel 102 so as to protrude outward in the width direction from the side edges of the left and right side flaps. Each pair of fastening parts 5 has a fixed end 51 that overlaps and is fixed to the side flap 102a, and a protruding part 52 that protrudes from the side edge of the side flap 102a. A locking member 53 is also provided on the skin-contacting side of the protruding part 52 of the fastening part 5. On the other hand, a front patch 8 is provided on the non-skin-contacting side of the front panel 101 for fastening the locking member 53 of the fastening part 5. Therefore, the tape-type disposable diaper 100 can be attached to the wearer by placing the back panel 102 against the wearer's back and the front panel 101 against the wearer's abdomen, and engaging the locking member 53 of the fastening part 5 attached to the back panel 102 with the front patch 8 provided on the front panel 101. The fastening part 5 and the front patch 8 may be engaged by an adhesive or adhesive tape, or they may constitute a mechanically coupled face-type fastener. For example, as the fastening mechanism for engaging the locking member 53 of the fastening part 5 and the front patch 8, it is particularly preferable to use a face-type fastener that is fixed by the mechanical coupling of a hook material (male member) and a loop material (female member). A face-type fastener is composed of, for example, a combination of a hook material having numerous protrusions (hook-shaped, mushroom-shaped, etc.) formed on its surface and a loop material having loop-shaped fibers arranged on its surface. For example, a hook material can be used as the locking member 53 of the fastening part 5, and a loop material can be formed on the outer surface of the front patch 8. In a face-type fastener, when the hook material is attached to the surface of the loop material, the numerous protrusions of the hook material engage with the surface of the loop material. Therefore, face-type fasteners are preferable because they can firmly fix the hook material and loop material in a way that allows for separation, and they are reusable and have high bonding strength.

[0031] The fastening portion 5 described above can also be attached to the side flap 101a of the front body 101 instead of the side flap 102a of the back body 102. In this case, the front patch 8 should be provided on the side of the back body 102 that does not come into contact with the skin. In addition, it is possible to provide not only one fastening portion 5 on each side, but also two or more pairs on each side.

[0032] In the present invention, an elastic sheet 4 is interposed between the top sheet 1 and the back sheet 2 in either the front panel 101 or the back panel 101, or in both the front panel 101 and the back panel 102. In the embodiment shown in Figure 1, the elastic sheet 4 is provided in the back panel 102 where the fastening portion 5 is located. The elastic sheet 4 has a structure that provides elasticity to the abdominal area of ​​the diaper. The configuration of the elastic sheet 4 will be described in detail below.

[0033] Figure 2 shows an outline of a cross-sectional view obtained by cutting a disposable diaper along the line Y1-Y1 shown in Figure 1. Figure 3 also shows an outline of a cross-sectional view obtained by cutting a disposable diaper along the line Y2-Y2 shown in Figure 1. Figures 2 and 3 mainly show the stretchable sheet 4 of a disposable diaper according to one embodiment. In Figures 2 and 3, the various sheet members constituting the disposable diaper are depicted with conceptual thickness, but in reality, the various sheet materials are very thin and have almost no thickness.

[0034] As shown in Figures 1 to 3, the stretchable sheet 4 is composed of a non-stretchable base sheet 41 and a plurality of stretchable yarn or strip-shaped elastic stretch members 42. The plurality of elastic stretch members 42 extend along the width direction of the diaper and are spaced apart in the length direction of the diaper, and are arranged between the base sheet 41 in an extended state. In the embodiment shown in Figure 2, the base sheet 41 is composed of a single sheet member and is folded back at a folded portion 41c located near the crotch area, forming an inner surface portion 41a located on the skin-contacting side and an outer surface portion 41b located on the non-skin-contacting side. The plurality of elastic stretch members 42 are sandwiched between the inner surface portion 41a and the outer surface portion 41b of the base sheet 41 in an extended state. Therefore, when the plurality of elastic stretch members 42 contract, the base sheet 41 also contracts under the influence of the contraction force, and highly cushioned gathers (folds) are formed in the stretchable sheet 4.

[0035] The stretchable sheet 4 having the basic configuration described above is interposed between the top sheet 1 and the back sheet 2. In particular, as shown in Figure 2, in this embodiment, a portion of the stretchable sheet 4 near the upper end of the back body 102 (upper part of Figure 2) is positioned between the top sheet 1 and the back sheet 2, and the other portion near the crotch (lower part of Figure 2) is positioned between the absorbent 3 and the back sheet 2. For this reason, in this embodiment, the outer surface portion 41b of the base sheet 41 of the stretchable sheet 4, which is located on the side that does not come into contact with the skin, is in full contact with the back sheet 2. On the other hand, the inner surface portion 41a of the base sheet 41 of the stretchable sheet 4, which is located on the side that comes into contact with the skin, is divided into a surface that comes into contact with the absorbent 3 (the surface located in the overlapping portion 43) and a surface that comes into contact with the top sheet (the surface located in the non-overlapping portion 44).

[0036] As shown in Figure 2, the base sheet 41 of the stretchable sheet 4 has an inner surface 41a that contacts the top sheet 1 and a surface that contacts the absorbent 3, and an outer surface 41b that contacts the back sheet 2. In this case, it is preferable that the inner surface 41a of the base sheet 41 and the top sheet 1 are continuously joined in the length direction and the width direction. It is also preferable that the outer surface 41b of the base sheet 41 and the back sheet 2 are continuously joined in the length direction and the width direction. In this way, because the base sheet 41 is continuously joined to the top sheet 1 and the back sheet 2, as the elastic stretchable member 42 sandwiched between the base sheet 41 contracts, fine gathers (folds) are formed on the top sheet 1 and the back sheet 2, improving the appearance and feel of the diaper and preventing the stretchable sheet 4 from shifting position.

[0037] On the other hand, the base sheet 41 and the absorbent 3 (core wrap sheet 32) may be joined continuously in the length direction and width direction, intermittently in the width direction, or not joined at all. In particular, in the present invention, it is preferable that the base sheet 41 and the absorbent 3 are not joined. By not joining the base sheet 41 to the absorbent 3, when the elastic stretch member 42 sandwiched between the base sheet 41 contracts, the contraction force is less likely to be transmitted to the absorbent 3, and the shape of the absorbent 3 is not deformed, preventing the occurrence of unnecessary wrinkles and creases. Furthermore, intermittently joining the base sheet 41 and the absorbent 3 in the width direction means that joined portions and non-joined portions are alternately provided between the base sheet 41 and the absorbent 3 along the width direction.

[0038] Furthermore, even if the base sheet 41 of the stretchable sheet 4 and the core wrap sheet 32 ​​of the absorbent 3 are not joined, it is preferable that the vicinity of the longitudinal edge of the absorbent 3 is joined to the base sheet 41. For example, it is preferable that the absorbent 3 is joined to the base sheet 41 in a longitudinal range of 1 mm to 30 mm, 5 mm to 25 mm, or 10 mm to 20 mm from the longitudinal edge 3' on the side that overlaps with the stretchable sheet 4, and that the rest of the absorbent 3 is not joined to the base sheet 41. By joining only the vicinity of the longitudinal edge of the absorbent 3 to the stretchable sheet 4 in this way, the end of the absorbent 3 is fixed and deformation of the absorbent 3 can be prevented.

[0039] As shown in Figures 1(a) and 1(b), in this embodiment, the stretchable sheet 4 interposed between the top sheet 1 and the back sheet 2 is divided in the longitudinal direction into an overlapping portion 43 near the crotch area 103 and a non-overlapping portion 44 near the edge of the back panel. The overlapping portion 43 of the stretchable sheet 4 is the portion that, when viewed in the width direction, includes an area that overlaps with a part of the absorbent 3. That is, as shown in Figures 1(a) and 1(b), the overlapping portion 43 is divided into a central region 43a that overlaps with the back panel side edge of the absorbent 3 and a lateral region 43b located outside the width direction of this central region 43a. For this reason, the elastic stretchable member 42 placed in the overlapping portion 43 of the stretchable sheet 4 overlaps with the absorbent 3 in the central region 43a, but does not overlap with the absorbent 3 in the lateral region 43b. On the other hand, the non-overlapping portion 44 of the stretchable sheet 4 is the portion that does not overlap with the absorbent 3 when viewed in the width direction. Therefore, the elastic stretch member 42 positioned in the non-overlapping portion 44 of the stretchable sheet 4 does not overlap with the absorbent 3. In this invention, a configuration in which the expandable sheet 4 is divided into an overlapping portion 43 and a non-overlapping portion 44 is preferred. The expandable sheet 4 only needs to have at least an overlapping portion 43 and does not necessarily need to have a non-overlapping portion 44.

[0040] In Figures 1(a) and 1(b), the portions of the multiple elastic stretch members 42 included in the stretchable sheet 4 that are joined between the base sheets 41 are shown with dotted lines, and the portions that are not joined between the base sheets 41 are shown with dashed lines. In Figures 2 and 3, the portions of the multiple elastic stretch members 42 included in the stretchable sheet 4 that are joined to the base sheets 41 are enclosed in circles (○). Figure 2 is a cross-sectional view along the Y1-Y1 line shown in Figure 1, and the cross-sectional boundary of Y1-Y1 is located in the central region 43a. Also, Figure 2 is a cross-sectional view along the Y2-Y2 line shown in Figure 1, and the cross-sectional boundary of Y2-Y2 is located in the lateral region 43b.

[0041] As shown in these figures, the multiple elastic stretch members 42 are arranged continuously in the overlapping portion 43 of the stretchable sheet 4. Here, "continuous" means that the elastic stretch members 42 extend from one side to the other along the width direction of the overlapping portion 43, and are arranged so that the entire structure is stretchable, and that the elastic stretch members 42 are not cut or compressed in the middle to become non-stretchable. The multiple elastic stretch members 42 arranged continuously in the overlapping portion 43 of the stretchable sheet 4 are not joined between the base sheet 41 in the central region 43a that overlaps with the absorber 3, while they are joined between the base sheet 41 in the lateral region 43b that does not overlap with the absorber 3. Thus, although the elastic stretch members 42 arranged in the overlapping portion 43 exist continuously in the width direction without interruption (without becoming non-stretchable), the portion located in the central region 43a is not joined to the base sheet 41, and the portion located in the lateral region 43b is joined to the base sheet 41. On the other hand, the multiple elastic stretch members 42 are also continuously arranged in the non-overlapping portions 44 of the stretchable sheet 4. The multiple elastic stretch members 42 arranged in the non-overlapping portions 44 of the stretchable sheet 4 exist continuously without interruption in the width direction and are joined between the base sheets 41.

[0042] In this invention, the elastic stretch member 42 included in the stretchable sheet 4 is basically bonded between the base sheet 41, except for the region (central region 43a) that overlaps with the absorbent 3 in the thickness direction. However, even in the region (central region 43a) where the stretchable sheet 4 and the absorbent 3 overlap, the elastic stretch member 42 exists in a stretchable state without being bonded between the base sheet 41. By adopting this configuration, the elastic stretch member 42 is also present in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap, and when the elastic stretch member 42 contracts, the absorbent 3 adheres closely to the wearer's skin. On the other hand, in the central region 43a where the stretchable sheet 4 and the absorbent 3 overlap, the elastic stretch member 42 is not bonded between the base sheet 41, so even when the elastic stretch member 42 contracts, the contracting force of the elastic stretch member 42 is less likely to be transmitted to the absorbent 3, preventing wrinkles and creases from forming in the absorbent 3.

[0043] A known method can be used to join the elastic stretch member 42 to the base sheet 41. As a method for joining the elastic stretch member 42, for example, one can be selected from a joining method using hot melt adhesive or a joining method using thermocompression. In the areas where joining is required (the lateral region 43b of the overlapping portion 43 and the non-overlapping portion 44), it is preferable that the elastic stretch member 42 is continuously joined to the base sheet 41. For example, hot melt adhesive can be applied to the necessary parts of the elastic stretch member 42, and the elastic stretch member 42 with the hot melt adhesive applied can be sandwiched between the base sheets 41.

[0044] Furthermore, as shown in Figures 1(a) and 1(b), it is preferable that the elastic stretch members 42 included in the stretchable sheet 4 are arranged between the base sheets 41 at approximately constant intervals in the longitudinal direction of the diaper. It is preferable that the intervals between adjacent elastic stretch members 42 are approximately the same, for example, 0.3 mm to 10 mm, or 0.5 mm to 0.8 mm. However, since it is practically difficult to perfectly match the intervals of multiple elastic stretch members 42, it is acceptable if the intervals are misaligned within an error range of ±5% or less when the average value of the intervals of multiple elastic stretch members 42 is taken as 100%. By making the intervals between the elastic stretch members 42 approximately constant in this way, uniform gathers (folds) are created around the waist of the diaper, improving its appearance and also improving the feel and texture of the diaper.

[0045] As shown in Figure 1(a), the stretchable sheet 4 is positioned at a distance from the longitudinal edge of the back panel 102 of the disposable diaper. The distance between the upper edge of the stretchable sheet 4 and the upper edge of the back panel of the disposable diaper is preferably, for example, 5 mm to 30 mm, or 10 mm to 20 mm. By positioning the stretchable sheet 4 at a distance from the longitudinal edge of the diaper in this way, the stiffness of the stretchable sheet 4 itself is less likely to be transmitted to the wearer, improving the comfort of wearing the diaper.

[0046] Furthermore, as shown in Figure 1(b), among the multiple elastic stretch members 42 included in the stretchable sheet 4, the elastic stretch members 42 located near the longitudinal edge 3' of the absorber 3 are designated as edge-near stretch members 42a. For example, among the multiple elastic stretch members 42, one to six elastic stretch members 42 that are close to the longitudinal edge 3' of the absorber 3 may be designated as edge-near stretch members 42a. In the example shown in Figure 1(b), four elastic stretch members 42 that are close to the longitudinal edge 3' of the absorber 3 are designated as edge-near stretch members 42a. In this case, it is preferable that the shrinkage force (A) that the edge-near stretch members 42a exert on the base sheet 41 is set lower than the shrinkage force of the other elastic stretch members 42. In other words, the area near the longitudinal edge 3' of the absorber 3 is particularly susceptible to deformation due to the influence of the contraction force of the elastic stretch member. Therefore, in order to suppress deformation of the absorber 3, it is preferable to set the contraction force (A) of the edge-near stretch member 42a to a lower level.

[0047] Furthermore, as shown in Figure 1(b), among the multiple elastic stretch members 42 arranged in the overlapping portion 43 of the stretchable sheet 4, the elastic stretch members other than the edge-near stretch member 42a described above are designated as overlapping elastic stretch members 42b. Also, among the multiple elastic stretch members 42 arranged in the non-overlapping portion 44 of the stretchable sheet 4, the elastic stretch members other than the edge-near stretch member 42a described above are designated as non-overlapping elastic stretch members 42c. In this case, it is preferable that the contraction force of the edge-near stretch member 42a (A), the contraction force of the overlapping elastic stretch member 42b (B), and the contraction force of the non-overlapping elastic stretch member 42c (C) satisfy the relationship (C) > (B) > (A). By having such a relationship, it is possible to provide appropriate elasticity to the abdominal area of ​​the diaper while keeping the amount of deformation of the absorbent body 3 affected by the contraction forces of the multiple elastic stretch members 42 small.

[0048] Alternatively, instead of the above relationship, the contraction force (A) of the edge-near expandable member 42a, the contraction force (B) of the superimposed elastic expandable member 42b, and the contraction force (C) of the non-superimposed elastic expandable member 42c can be adjusted to satisfy the relationship (B) > (C) > (A). In this case, deformation near the longitudinal edge 3' of the absorber 3 can be kept small while providing high expandability to the sides (lateral region 43b) of the absorber 3.

[0049] The above-mentioned "shrinkage force" can be adjusted, for example, by adjusting the elongation rate when joining the elastic stretch members to the base sheet, if multiple elastic stretch members of the same thickness are used. The "elongation rate" here refers to the ratio of the increase in length of the elastic stretch member in the stretched state, with the length of the elastic stretch member in the contracted state (natural state) being 100%. For example, if a 10 cm long member is stretched to 20 cm, the elongation rate is 200%. The higher the elongation rate of the elastic stretch member when it is joined to the base sheet, the higher the shrinkage force of the elastic stretch member. It is also possible to adjust the shrinkage force of the elastic stretch member by adjusting its thickness. Due to its properties, for the same elongation rate, the thicker the elastic stretch member, the stronger the shrinkage force.

[0050] The above-mentioned "shrinkage force" refers to the stress applied to the base sheet when the elastic stretchable member is joined to the base sheet while stretched in the width direction of the diaper. The shrinkage force of the elastic stretchable member can be measured as follows. First, a region to be measured is cut from the stretched sheet to be used as a test specimen. One end of this test specimen in the width direction is clamped in one chuck of a tensile testing machine, and the other end is clamped in the other chuck, and a tensile test is performed along the width direction. Then, the distance between the chucks when the test specimen is naturally contracted without being pulled is defined as α (length during natural contraction), and the distance between the chucks when the test specimen is pulled to a state where there is no contraction by the elastic stretchable member is defined as β (length during maximum stretch). The stress applied between the chucks when the test specimen is pulled so that the distance between the chucks is (α + β) / 2 is measured, and this is divided by the length of the test specimen in the front-to-back direction to obtain the shrinkage force. In this way, the levels of stretching force of each elastic stretchable member can be compared.

[0051] As shown in Figure 1(a), a pair of fastening parts 5 are attached to each of the left and right side flaps 102a formed on the back panel 102 of the disposable diaper 100. The stretchable sheet 4 is also positioned on the back panel 102 of the disposable diaper 100, similar to the pair of fastening parts 5. In this case, it is preferable that the multiple elastic stretchable members 42 included in the stretchable sheet 4 do not overlap the fixed ends 51 of the pair of fastening parts 5, but are located in the area inside the fixed ends 51 in the width direction. By providing the elastic stretchable members 42 of the stretchable sheet 4 in the area inside the fixed ends 51 in the width direction of the pair of fastening parts 5 in this way, when the fastening parts 5 are pulled when putting on the disposable diaper, the waist circumference of the diaper stretches, making it easier to put on tape-type disposable diapers.

[0052] Furthermore, as shown in Figure 1(a), it is preferable that the ends on both sides in the width direction of the base sheet 41 constituting the stretchable sheet 4 overlap in the thickness direction with the fixed ends 51 of the pair of fastening parts 5. That is, as shown in Figure 1(a), although the elastic stretchable member 42 of the stretchable sheet 4 does not overlap with the fixed ends 51 of the fastening parts 5, both ends in the width direction of the base sheet 41 overlap with the fixed ends 51 of the fastening parts 5. With this configuration, when the pair of fastening parts 5 are pulled outward in the width direction, the tensile force is more easily transmitted to the base sheet 41 of the stretchable sheet 4. And when the tensile force in the width direction is appropriately transmitted to the base sheet 41 of the stretchable sheet 4, the elastic stretchable member 42 sandwiched between the base sheets 41 is more easily stretched outward in the width direction. For this reason, the work of attaching tape-type disposable diapers becomes even easier.

[0053] Next, with reference to Figures 4 and 5, an embodiment in which a plurality of elastic stretch members 42 are sandwiched between base sheets 41 will be described. Figures 4 and 5 show examples of variations applicable to the present invention. However, the embodiment in which a plurality of elastic stretch members 42 are sandwiched between base sheets 41 is not limited to those described below. Figures 4 and 5 show the cross-sectional shape of the stretch sheet 4 when it is cut in the longitudinal direction at the central region 43a of the stretch sheet 4, similar to the cross-sectional view in Figure 2. Also, in Figures 4 and 5, the absorbent 3 is indicated by a "dotted line" to clarify the arrangement relationship between the stretch sheet 4 and the absorbent 3.

[0054] The stretchable sheet 4 shown in Figure 4(a) has the same configuration as the stretchable sheet 4 shown in Figure 2. That is, in the example shown in Figure 4(a), the base sheet 41 of the stretchable sheet 4 is made of a single sheet member. The base sheet 41 is folded over at a folded portion 41c located at the crotch area (lower side in Figure 4), and is divided into an inner surface portion 41a located on the skin-contacting side and an outer surface portion 41b located on the non-skin-contacting side, with the folded portion 41c as the boundary. The upper edge side (upper side in Figure 4) of the base sheet 41 is open, and there is no portion where the sheet members overlap twice. The configuration in which the base sheet 41 is folded in half to sandwich the elastic stretchable member 42, as shown in Figure 4(a), is generally also called a U-wrap structure.

[0055] In the example shown in Figure 4(a), the base sheet 41 and the absorbent 3 may be joined continuously in the length and width directions, intermittently in the width direction, or not joined at all. In particular, in the present invention, it is preferable that the base sheet 41 and the absorbent 3 are not joined. By not joining the base sheet 41 to the absorbent 3, when the elastic stretch member 42 sandwiched between the base sheet 41 contracts, the contraction force is less likely to be transmitted to the absorbent 3, preventing deformation of the shape of the absorbent 3 and the occurrence of unnecessary wrinkles and creases. Furthermore, even if the base sheet 41 of the stretch sheet 4 and the core wrap sheet 32 ​​of the absorbent 3 are not joined, it is preferable that the vicinity of the longitudinal edge of the absorbent 3 is joined to the base sheet 41. For example, it is preferable that the absorbent 3 is bonded to the base sheet 41 in a longitudinal range of 1 mm to 30 mm, 5 mm to 25 mm, or 10 mm to 20 mm from the longitudinal edge 3' on the side that overlaps with the stretchable sheet 4, and not bonded to the base sheet 41 in other parts.

[0056] Figure 4(b) shows an example in which the base sheet 41 is composed of two sheet members. As shown in Figure 4(b), the inner surface 41a and the outer surface 41b of the base sheet 41 can also be composed of separate sheet members. In this way, a plurality of elastic stretch members 42 may be sandwiched between the sheet member that constitutes the inner surface 41a and the sheet member that constitutes the outer surface 41b. In the example shown in Figure 4(b), the base sheet 41 and the absorber 3 may be joined continuously in the length direction and width direction, or intermittently in the width direction, or may not be joined at all. In particular, it is preferable that the absorber 3 is joined to the base sheet 41 near the longitudinal edge 3' on the side that overlaps with the stretch sheet 4, and not joined to the base sheet 41 in other parts.

[0057] Figure 4(c) shows an example in which the base sheet 41 is made up of a single sheet member and has an intersection 41d that crosses between the elastic stretch members 42 in the thickness direction (left-right direction in Figure 4). Specifically, in the example shown in Figure 4(c), the base sheet 41 is divided into a lower part 41e closer to the crotch area in the length direction (lower side in Figure 4) and an upper part 41f closer to the length direction (upper side in Figure 4), with the intersection 41d as the boundary. In the lower part 41e of the base sheet 41, the lower inner surface 41g located on the skin contact side and the lower outer surface 41h located on the non-skin contact side are integrally connected via a lower edge folded portion 41i corresponding to the lower edge of the stretch sheet 4. A plurality of elastic stretch members 42 are arranged between these lower inner surface 41g and lower outer surface 41h. Furthermore, in the upper part 41f of the base sheet 41, the upper inner surface 41j located on the skin-contacting side and the upper outer surface 41k located on the non-skin-contacting side are integrally connected via an upper edge folded portion 41l corresponding to the upper edge of the stretchable sheet 4. Multiple elastic stretchable members 42 are arranged between these upper inner surface 41j and upper outer surface 41k. In the example shown in Figure 4, the lower inner surface 41g and the upper outer surface 41k of the stretchable sheet 4 are integrally connected via an intersection portion 41d that crosses the elastic stretchable members 42 in the thickness direction. In another example, the lower outer surface 41h and the upper inner surface 41j of the stretchable sheet 4 may be integrally connected via the intersection portion 41d. Thus, in the example shown in Figure 4(c), the base sheet 41 has a roughly figure-eight cross-section. In particular, as shown in Figure 4(c), it is preferable that the intersection 41d is formed at a position that crosses in the thickness direction between the elastic stretch member 42 located in the overlapping portion 43 that overlaps with the absorber 3 and the elastic stretch member 42 located in the non-overlapping portion 44 where the absorber 3 does not overlap. With this configuration, the elastic stretch member 42 is joined between the sheets in the upper part 41f of the base sheet 41, but the elastic stretch member 42 is not joined between the sheets in the lower part 41e of the base sheet 41.In this way, by forming an intersection 41d that separates the elastic stretch member 42 that is joined between the sheets and the elastic stretch member 42 that is not joined between the sheets, the contraction force of the elastic stretch member 42 located at the upper part 41f of the base sheet 41 is less likely to be transmitted to the absorber 3 that is in contact with the lower part 41e of the base sheet 41. Therefore, the amount of deformation of the absorber 3 can be suppressed. In the example shown in Figure 4(c), the base sheet 41 and the absorber 3 may be joined continuously in the length direction and width direction, intermittently in the width direction, or not joined at all. In particular, it is preferable that the absorber 3 is joined to the base sheet 41 near the longitudinal edge 3' on the side that overlaps with the stretch sheet 4, and not joined to the base sheet 41 in other parts.

[0058] Figure 5 shows a further modification of the embodiment shown in Figure 4. Figure 5(a) shows an application example of the structure of the stretchable sheet 4 described with reference to Figure 4(c). In the example shown in Figure 5, the upper inner surface 41j of the base sheet 41 has an extended portion 41m that extends in the direction of the crotch area (downward in Figure 5). The extended portion 41m of the upper inner surface 41j overlaps with the lower inner surface 41g of the base sheet 41. Therefore, in the overlapping portion 43 where the base sheet 41 overlaps with the absorber 3, the elastic stretchable member 42 and the absorber 3 overlap more than twice. That is, the extended portion 41m of the upper inner surface 41j and the lower inner surface 41g of the base sheet 41 are located between the elastic stretchable member 42 and the absorber 3, which are positioned in the overlapping portion 43. By adopting such a configuration, for example, even if the extended portion 41m of the upper inner surface 41j of the base sheet 41 is joined to the absorber 3, if the extended portion 41m and the lower inner surface 41g are not joined, the contraction force of the elastic stretchable member 42 can be less easily transmitted to the absorber 3. In other words, the lower inner surface 41g that is in direct contact with the elastic stretch member 42 is easily compressed by the contraction force of the elastic stretch member 42, but the contraction force of the elastic stretch member 42 is less likely to be transmitted to the extended portion 41m that is superimposed on the lower inner surface 41g without being joined to it. Therefore, the absorber 3 superimposed on the extended portion 41m is less affected by the contraction force of the elastic stretch member 42. In this way, by superimposing two or more base sheets 41 between the elastic stretch member 42 placed in the superimposed portion 43 and the absorber 3, it is possible to prevent wrinkles and creases from forming in the absorber 3.

[0059] However, in the example shown in Figure 5(a), the extended portion 41m of the base sheet 41 and the absorber 3 may be joined continuously in the length direction and width direction, intermittently in the width direction, or not joined at all. Also, the extended portion 41m of the base sheet 41 and the lower inner surface 41g may be joined continuously in the length direction and width direction, intermittently in the width direction, or not joined at all. For example, it is preferable to continuously join the extended portion 41m of the base sheet 41 to the absorbent 3, but not to join the extended portion 41m to the lower inner surface 41g. By joining the extended portion 41m of the base sheet 41 to the absorbent 3, deformation and displacement of the absorbent 3 can be prevented. Furthermore, by not joining the extended portion 41m to the lower inner surface 41g, when the elastic stretchable member 42 sandwiched between the base sheet 41 contracts, the contraction force is less likely to be transmitted to the absorbent 3, preventing deformation of the absorbent 3 and the occurrence of unwanted wrinkles and creases. Furthermore, for example, the extended portion 41m of the base sheet 41 and the absorbent 3 may not be joined, but the extended portion 41m and the lower inner surface 41g may be joined. However, even if the extended portion 41m of the base sheet 41 of the expandable sheet 4 and the absorbent 3 are not joined, it is preferable that the vicinity of the longitudinal edge of the absorbent 3 is joined to the extended portion 41m in order to prevent deformation of the absorbent 3. For example, it is preferable that the absorbent 3 is joined to the extended portion 41m of the base sheet 41 in longitudinal ranges of 1 mm to 30 mm, 5 mm to 25 mm, or 10 mm to 20 mm from the longitudinal edge on the side overlapping with the expandable sheet 4, and that the other parts are not joined to the extended portion 41m of the base sheet 41. Furthermore, for example, the extended portion 41m of the base sheet 41 and the absorbent 3 may not be joined, nor may the extended portion 41m and the lower inner surface 41g be joined. However, even if the extended portion 41m of the base sheet 41 of the expandable sheet 4 and the absorbent 3 are not joined, it is preferable that the vicinity of the longitudinal edge of the absorbent 3 is joined to the extended portion 41m.

[0060] Figure 5(b) shows another example of the structure of the stretchable sheet 4. In the example shown in Figure 5(b), the base sheet 41 is made up of a single sheet member, and the inner surface portion 41a and the outer surface portion 41b are integrally connected via an upper edge folded portion 41l corresponding to the upper edge of the stretchable sheet 4. Multiple elastic stretchable members 42 are sandwiched between these inner surface portion 41 and outer surface portion 41b. Furthermore, the outer surface portion 41b has an extended portion 41m that extends in the direction where the crotch area is located (downward in Figure 5). The extended portion 41m of the outer surface portion 41b is folded back toward the skin contact surface at the lower edge folded portion 41i corresponding to the lower edge of the stretchable sheet 4, and overlaps with the inner surface portion 41a. As a result, the base sheet 41 overlaps more than twice between the elastic stretchable members 42 and the absorbent 3 in the overlapping portion 43 that overlaps with the absorbent 3. In other words, the inner surface portion 41a and the extended portion 41m of the outer surface portion 42b of the base sheet 41 are located between the elastic stretchable member 42 positioned in the overlapping portion 43 and the absorber 3. By adopting this configuration, for example, even if the extended portion 41m of the outer surface portion 41b of the base sheet 41 is joined to the absorber 3, if the extended portion 41m and the inner surface portion 41a are not joined, the contraction force of the elastic stretchable member 42 will not be easily transmitted to the absorber 3. This point is the same as in the example of Figure 5(a) described above.

[0061] In the example shown in Figure 5(b), as in the example shown in Figure 5(a) above, the extended portion 41m of the base sheet 41 and the absorber 3 may be joined continuously in the length direction and width direction, or intermittently in the width direction, or may not be joined at all. Also, the extended portion 41m of the base sheet 41 and the lower inner surface 41g may be joined continuously in the length direction and width direction, or intermittently in the width direction, or may not be joined at all. For example, it is preferable to continuously join the extended portion 41m of the base sheet 41 to the absorbent 3, but not to join the extended portion 41m to the lower inner surface 41g. Alternatively, for example, the extended portion 41m of the base sheet 41 may not be joined to the absorbent 3, but the extended portion 41m may be joined to the lower inner surface 41g. However, even if the extended portion 41m of the base sheet 41 of the expandable sheet 4 and the absorbent 3 are not joined, it is preferable that the vicinity of the longitudinal edge of the absorbent 3 is joined to the extended portion 41m in order to prevent deformation of the absorbent 3. Furthermore, for example, the extended portion 41m of the base sheet 41 may not be joined to the absorbent 3, and the extended portion 41m may not be joined to the lower inner surface 41g either.

[0062] Next, with reference to Figure 6, yet another modified example of the structure of the expandable sheet 4 will be described. In the example shown in Figure 6(a), the base sheet 41 constituting the stretchable sheet 4 is folded in half at the folded portion 41c, and has an inner portion 41a located on the skin-contacting side and an outer portion 41b located on the non-skin-contacting side. Between the inner portion 41a and the outer portion 41b of the base sheet 41, a plurality of elastic stretchable members 42 are arranged at regular intervals in the longitudinal direction (vertical direction in Figure 6). The inner portion 41a and the outer portion 41b of the base sheet 41 are joined to each other in the region of the gap between adjacent elastic stretchable members 42. That is, a joint portion 41n between the inner portion 41a and the outer portion 41b is formed in the region of the gap between adjacent elastic stretchable members 42. By joining the inner portion 41a and the outer portion 41b of the base sheet 41 in the region between the elastic stretchable members 42 arranged at intervals in this way, it is possible to prevent the elastic stretchable members 42 from shifting in the longitudinal direction of the diaper. In particular, in the present invention, since the elastic stretch member 42 positioned in the overlapping portion 43 that overlaps with the absorber 3 is not joined to the base sheet 41, it is preferable to restrict the displacement of the elastic stretch member by some method. Therefore, in the example shown in Figure 6(a), a joint n is formed in the gap between adjacent elastic stretch members 42 by joining the inner surface 41a and the outer surface 41b of the base sheet 41, thereby preventing displacement of the elastic member. The inner surface 41a and the outer surface 41b may be joined, for example, using a hot melt adhesive, or by heat sealing or ultrasonic sealing.

[0063] In the example shown in Figure 6(b), the base sheet 41 constituting the stretchable sheet 4 is folded in half at the folded portion 41c, and has an inner portion 41a located on the skin-contacting side and an outer portion 41b located on the non-skin-contacting side. Between the inner portion 41a and the outer portion 41b of the base sheet 41, a plurality of elastic stretchable members 42 are arranged at regular intervals in the longitudinal direction (up and down direction in Figure 6). The sheet member constituting the outer portion 41b (or inner portion 41a) is deformed to form a plurality of protrusions 41o that project toward the elastic stretchable members 42 in the region of the gap between adjacent elastic stretchable members 42. For example, the protrusions 41o can be formed by deforming the base sheet 41 so that it is convex toward the side facing the elastic stretchable members 42.

[0064] In the example shown in Figure 6(c), the base sheet 41 constituting the stretchable sheet 4 is folded in half at the folded portion 41c, and has an inner surface portion 41a located on the skin-contacting side and an outer surface portion 41b located on the non-skin-contacting side. Between the inner surface portion 41a and the outer surface portion 41b of the base sheet 41, a plurality of elastic stretchable members 42 are arranged at regular intervals in the longitudinal direction (up and down direction in Figure 6). Then, in the region of the gap between adjacent elastic stretchable members 42, a heated needle (heat needle N) is passed through from the inner surface portion 41a toward the outer surface portion 41b to create a plurality of perforations 41p, thereby heat-bonding the inner surface portion 41a and the outer surface portion 41b. The size of the perforations 41p is preferably 0.2 mm to 0.5 mm in diameter when the sole purpose is heat-bonding the inner surface portion 41a and the outer surface portion 41b. Furthermore, if the purpose is to provide breathability to the expandable sheet 4 by perforating 41p, the size of the perforation 41p is preferably 0.5 mm to 10 mm in diameter. By providing relatively large perforations 41p in the expandable sheet 4, the breathability and moisture permeability in the thickness direction of the expandable sheet 4 are improved. To adjust the size of the perforation 41p, a heat needle N having a cross-sectional diameter suitable for the purpose can be selected to form the perforation 41p. In this way, by providing perforations 41p with the heat needle N in the region of the gap between adjacent elastic expandable members 42, and by heat bonding the inner surface 41a and the outer surface 41b, displacement of the elastic expandable members 42 can be prevented.

[0065] Figure 6(d) differs from Figures 6(a) to (c) above in that it is a cross-sectional view showing the state in which the stretchable sheet 4 has been cut along the width direction of the disposable diaper in which the elastic stretchable member 42 is stretched. In the example shown in Figure 6(d), the base sheet 41 that constitutes the stretchable sheet 4 is folded in half and has an inner surface portion 41a located on the skin-contacting side and an outer surface portion 41b located on the non-skin-contacting side, and a plurality of elastic stretchable members 42 are arranged between the inner surface portion 41a and the outer surface portion 41b. In the example shown in Figure 6(d), before sandwiching the stretched elastic stretchable member 42 between the inner surface portion 41a and the outer surface portion 41b of the base sheet 41, the base sheet 41 is subjected to fine wrinkle-like deformation so that irregularities are formed in the thickness direction of the sheet member. Then, with the wrinkles remaining in the base sheet 41, the stretched elastic stretchable member 42 is sandwiched and fixed between the inner surface portion 41a and the outer surface portion 41b. In this way, the stretchable sheet 4 with the structure shown in Figure 6(d) is formed. As in the example described above, in a normal stretchable sheet 4, gathers are formed when the elastic stretchable member 42 is contracted, and it has cushioning properties in the thickness direction. However, in a normal stretchable sheet 4, gathers are not formed when the elastic stretchable member 42 is fully stretched, and cushioning properties in the thickness direction cannot be expected. Therefore, in the example shown in Figure 6(d), in order to make the base sheet 41 have cushioning properties even when the elastic stretchable member 42 is fully stretched, fine wrinkle-like deformation is applied to the base sheet 41 before sandwiching the elastic stretchable member 42 between the inner surface 41a and the outer surface 41b. As a result, even when the elastic stretchable member 42 is fully stretched, wrinkles that are uneven in the thickness direction remain on the base sheet 41, so that the stretchable sheet 4 always has appropriate cushioning properties.

[0066] The material of the base sheet 41 constituting the above-described expandable sheet 4 can be appropriately a known material. For example, the base sheet 41 is preferably hydrophobic. Examples of the material constituting the base sheet 41 include a non-woven fabric or a film. Further, as the raw material for forming the base sheet 41, polyethylene, polypropylene, polyester, or the like can be used, but is not limited thereto. When the base sheet 41 is made of a non-woven fabric, it can be obtained by making a raw material such as polyethylene into a fibrous form, accumulating, and bonding. Specific examples of the method for obtaining the non-woven fabric include the spunbond method, the spunbond-meltblown-spunbond method (SMS method), the air-through method, or the point bond method. When the base sheet 41 is made of a film, it is most preferable to use a polyethylene film. In addition, as the base sheet 41, a laminated product of a non-woven fabric and a film may be used.

[0067] Also, the material of the elastic expansion and contraction member 42 constituting the expandable sheet 4 can be appropriately a known material. For example, a filamentous elastic rubber or a flat elastic rubber can be applied to the elastic expansion and contraction member 42. As such a rubber member, materials such as styrene rubber, olefin rubber, urethane rubber, ester rubber, polyurethane, polyethylene, polystyrene, styrene butadiene, silicone, or polyester can be used. In addition, for each expansion and contraction member, a known member having elasticity such as a thermoplastic elastomer, a plastic sheet, or a rubber sheet can also be used. Further, the number of the elastic expansion and contraction members 42 arranged between the base sheets 41 can be appropriately adjusted according to the application. For example, the elastic expansion and contraction member 42 may be 4 to 20, 8 to 16, 10 to 14, or 12.

[0068] As described above, in this specification of the present application, in order to express the content of the present invention, the preferred embodiments of the present invention have been mainly described while referring to the drawings. However, the present invention is not limited to the above-described embodiments, and includes obvious modification forms and improvement forms that can be made by those skilled in the art based on the matters described in this specification.

[0069] For example, in this specification, the disposable diaper has been described by taking the case where it is a tape type as an example. However, the disposable diaper is not limited to the tape type. For example, the present invention is also applicable to a pant-type disposable diaper. The pant-type disposable diaper has a front body, a back body, and a crotch portion located between them. By previously joining the both side portions in the width direction of the front body and the both side portions in the width direction of the back body in correspondence, it is a type of diaper in which an opening around the abdomen and openings around both legs are formed. The pant-type disposable diaper is worn by inserting both legs of the wearer from the opening around the abdomen and taking out the respective legs from the openings around the left and right legs. Thus, when the disposable diaper of the present invention is a pant type, the above-described stretch sheet peculiar to the present invention may be disposed on both or either one of the abdominal circumferential portions of the front body and the back body.

[0070] The present invention relates to, for example, a disposable diaper for the elderly or infants. Therefore, the disposable diaper of the present invention can be suitably used in industries related to caregiving and childcare.

[0071] 1... Top sheet 2... Back sheet 3... Absorbent body 4... Stretch sheet 5... Fixing portion 6... Side sheet 7... Cover sheet 8... Front patch 41... Base material sheet 42... Elastic stretch member 43... Overlapping portion 43a... Central region 43b... Lateral region 44... Non-overlapping portion 51... Fixed end 52... Protrusion 53... Locking member 61... Three-dimensional gather stretch member 62... Leg-around gather stretch member 100... Disposable diaper

Claims

[1] A liquid-permeable topsheet (1), A liquid-impermeable backsheet (2), An absorber (3) interposed between the topsheet (1) and the backsheet (2) in a region including the crotch, A stretch sheet (4) interposed between the topsheet (1) and the backsheet (2) in a region of either or both of the front body and the back body, and including a region overlapping a part of the absorber (3), A disposable diaper comprising: The stretch sheet (4) has a base sheet (41), and a plurality of elastic stretch members (42) extending along the width direction of the disposable diaper and arranged in an extended state at intervals in the length direction of the disposable diaper, disposed between the base sheets (41), The stretch sheet (4) has an overlapping portion (43) including a region overlapping a part of the absorber (3) when viewed in the width direction, The plurality of elastic stretch members (42) are continuously arranged along the width direction in the overlapping portion (43), in a central region (43a) of the overlapping portion (43) that overlaps a part of the absorber (3), are not joined between the base sheets (41), in a side region (43b) of the overlapping portion (43) located outside the central region (43a) in the width direction, are joined between the base sheets (41) Disposable diaper. [2] The stretchable sheet (4) is When viewed in the width direction, it further includes a non-overlapping portion (44) that does not overlap with the absorbent (3), The plurality of elastic stretch members (42) are, In the non-overlapping portion (44), it is arranged continuously along the width direction and bonded between the base sheet (41). A disposable diaper according to claim 1. [3] The front or back of the garment is further provided with at least one pair of fastening portions (5) attached to both the left and right sides so as to protrude outward from the left and right side edges in the width direction, The aforementioned expandable sheet (4) is It is positioned in the part of the front or back of the garment that has the fastening portion (5) provided. The plurality of elastic stretch members (42) included in the stretchable sheet (4) are The fastening portion (5) is located inward in the width direction from the fixed ends fixed to the left and right sides. A disposable diaper according to claim 1 or claim 2. [4] The plurality of elastic stretch members (42) included in the stretchable sheet (4) are They are arranged at approximately constant intervals along the aforementioned length. A disposable diaper according to any one of claims 1 to 3. [5] The stretchable sheet (4) is They are spaced apart from the edges in the longitudinal direction of the front or back bodice. A disposable diaper according to any one of claims 1 to 4. [6] The base sheet (41) included in the stretchable sheet (4) is In the overlapping portion (43), the elastic stretchable member (42) and the absorber (3) overlap more than twice. A disposable diaper according to any one of claims 1 to 5.

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